184 FUNGI. 



able. Therefore another method of examination was adopted ; 

 the spores of a certain form were sown, and sooner or later they 

 were looked after to see what the seed had produced — not every 

 single spore — but the seed en masse, that is, in other words, 

 what had grown on that place where the seed had been sown. 

 As far as it relates to those forms which are so widely spread, - 

 and above all grow in conjunction with one another — and that 

 is always the case in the specimens of which we speak — we can 

 never be sure that the spores of the form which we mean to test 

 are not mingled with those of another species. He who has 

 made an attentive and minute examination of this kind knows 

 that we may be sure to find such a mixture, and that such an 

 one was there can be afterwards decidedly proved. From the 

 seed which is sown, these spores, for which the substratum was 

 most suitable, will more easily germinate, and their development 

 will follow the more quickly. The favoured germs will suppress 

 the less favoured, and grow up at their expense. The same 

 relation exists between them as between the seeds, germs, and 

 seedlings of a sown summer plant, and the seeds which have 

 been undesignedly sown with it, only in a still more striking 

 manner, in consequence of the relatively quick development "of 

 the mildew fungus. 



Therefore, that from the latter a decided form, or a mixture of 

 several forms, "is to be found sown on one spot, is no proof of their 

 generic connection with one which has been sown for the purpose 

 of experiments ; and the matter will only be more confused if we 

 call imagination to our aid, and place the forms which are found 

 near one another, according to a real or fancied resemblance, in a 

 certain series of development. All those statements on the sphere 

 of form and connection, which have for their basis such a super- 

 ficial work, and are not based on the clear exposition Of the conr- 

 tinuity of development, as by the origin of the connection of the 

 Mucor with Penicillium, Oidium lactis and Mucor, Oidium and 

 Penicillium, are rejected as unfounded. 



A source of error, which can also interfere in the last-named 

 superficial method of cultivation for experiments, is, viz., that 

 heterogeneous unwished-for spores intrude themselves from 



